Convert Sorted Array to Binary Search Tree.md

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example:

Given the sorted array: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

      0
     / \
   -3   9
   /   /
 -10  5

My code:

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
   def sortedArrayToBST(self, nums):
       """
       :type nums: List[int]
       :rtype: TreeNode
       """
       if nums==None:
           return None
       
       tree=self.build_tree(nums)
       return tree
   def build_tree(self,nums):
       if nums==None or len(nums)==0:
           return None
       mid=int(len(nums)/2)
       root=TreeNode(nums[mid])
       
       root.left=self.build_tree(nums[0:mid])
       root.right=self.build_tree(nums[mid+1:])        
       return root

Solution: https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/